274 THE PENOKEE IRON BEARING SERIES. 



ent mines, while doubtless there are many more. In quite a number of 

 mines, as, tor instance, the Trim))le (PI. xxxi, Figs. 4 and 5), NE. J, See. 33, 

 T. 46 N., R. 2 E.,Wisconshi, there are at least three parallel dikes. In those 

 cases in which there are several dikes in a single mine, one is generally known 

 as the iiiiiin dike. The smaller ones are, in some cases, clearly offshoots 

 from the larger, the actual connections between tliem being traced; while 

 in many other cases there is no certain connection between the different 

 dikes in the same mine. 



Position of ore in rcfci'dicr to the (Jikfs. — I'he ore has been spoken of as 

 resting upon the fragmental quartzite as a foot wall and in exceptional 

 cases (the so-called " north veins") as resting upon n (piai'tz rock which 

 belongs to the iron formatitm, but which nevertheless forms a foot wall for the 

 ore deposits dipping north with the formation. From the description of the 

 position of the dikes and the quartzites, it is evident that the two rocks form 

 V-shaped troughs, which liave at their apices right angles, and the south 

 arms of which are nearer vertical than the north arms, the first being 

 upon an average 20° to 30° from a vertical, while the second is 20° to 30° 

 from a horizontal position. The relation is that of a right-angled trough 

 tilted toward the north until it lacks 20° to 30° from having its ai-ms in 

 horizontal and vertical positi(_ins. In one or two mines, for a short distance 

 these troughs do not incline either east or west, but at most of tliem, from 

 what has gone Isefore, it is evident that they incline to the east. In one 

 case, however, there is a westward inclination. Now, the ore hodivfi lie in 

 flic apircs of these rowjhlij shaped troiK/hs. Each deposit of ore in following 

 a trough will e\idently be at different de})ths at different places east and 

 west, the de[)th depending upon the nearness of the dikes to the surface. 

 All ore dej)osits in the position described would reach the siu'face if the 

 underlying dikes pitch to the east or to the west. As a matter of fact, many 

 of them were fomid at the rock surface, but others were found after cut- 

 ting an overlying rock. However, at present (October, 1888), the mining- 

 developments have traced to the surface all deposits which are large enough 

 to warrant working, witJi two exceptions, and these exceptions are 

 n(!wly disc(»vered bodies, wliicli, in all probability, will be traced to the 

 surface in tlu^ future. As would be expected, it is also true that the devel- 



